1. Field of the Invention
The present invention relates to a medical instrument used to implant seeds, such as radioactive seeds, into a patient""s body. In particular, the present invention relates to a needle hub configuration for a medical instrument.
2. Description of the Related Art
For treating prostate cancer, radioactive seeds are provided to various locations within a patient""s prostate gland, by way of a medical instrument, also called a seed implantation device. Typically, a base unit which includes an ultrasound unit is used to determine the exact location of the patient""s prostate gland with respect to the base unit. The base unit is capable of being moved either towards the patient or away from the patient.
The ultrasound unit includes a probe, which is inserted into the patient""s rectum while the patient is lying on his back. A grid template is mounted onto the base unit, whereby the grid template includes a plurality of rows and columns of needle holes in which a needle can be inserted. Typically, the grid template includes a 13 by 13 matrix of needle holes, whereby adjacent holes on a row or a column are spaced 5 mm apart. Every other row is labeled with a number (e.g., 1, 2, etc.) on the grid template, and every other column is labeled with an alphabetic character (e.g., A, B, etc.). There is a direct relation between the centerline axis of the ultrasound probe and the position of the holes of the grid template.
Based on information obtained from the ultrasound unit, a needle is positioned through a particular hole (e.g., B5 hole) on the grid template, and then the needle is inserted into a region within the patient""s body in which the prostate gland is located. By using the ultrasound unit, a precise position of the proximal and distal positions (relative to the ultrasound unit) of the prostate gland can be determined and recorded. The distal position (relative to the ultrasound unit) of the prostate gland is also called the xe2x80x9czero retraction pointxe2x80x9d. Once the prostate gland position information is obtained, a seed implantation plan can be determined by a doctor, where the plan corresponds to a sequential process for injecting seeds into particular locations within the patient""s prostate gland. Such treatment is generally started by placing the end of the needle (e.g., bevel end of a bevel needle or the end of a trocar needle) at the zero retraction point, and then start applying seeds with respect to that reference point.
For a conventional seed implantation device, a needle is first placed into a particular needle hole of a grid template, and then the seed implantation device is held in place by a doctor and attached to the needle. The seed implantation device is then used to inject one or more seeds into the patient""s body through the needle. When finished with that hole, the seed implantation device is detached from the needle, and placed aside. Then, the needle is removed from the grid template, and a new needle is positioned at another needle hole of the grid template, according to the specific plan for treating the patient""s prostate gland. Alternatively, some physicians prefer to insert an entire row of needles onto the grid template, and thereby move from needle to needle. Other physicians implant all needles required at the deepest depth position, and then continue with all needles required at the next-deepest depth position, and so forth. One conventional seed implantation device is called a MICK applicator, and requires the operator to physically reposition the MICK applicator back onto a new needle positioned onto the grid template. Such an applicator is described in U.S. Pat. No. 5,860,909, entitled Seed Applicator for Use in Radiation Therapy.
As described above, the needle is attached to the medical instrument, and in particular, to a distal end of the medical instrument. The coupling of the needle to the medical instrument is an important element in being able to properly implant seeds into a patient.
One object of the present invention is to provide a needle hub configuration, whereby a needle can be attached to the medical instrument in a fairly easy manner, and also allow for proper orientation of the needle to be able to implant seeds properly.
This object may be achieved by an apparatus for coupling a needle to a medical instrument. The apparatus includes a needle hub that is coupled to the needle, the needle hub having a plurality of cam registration ribs on an outer surface thereof. The apparatus also includes a needle cam that has a plurality of hub registration ribs on an inner surface thereof. The apparatus further includes a needle nozzle disposed at a distal end of the medical instrument, the needle nozzle being configured to hold the needle cam in place within the needle nozzle. The cam registration ribs are fitted between the hub registration ribs to provide a coupling of the needle to the medical instrument.
The above-mentioned object may also be achieved by an apparatus for coupling a needle to a medical instrument. The apparatus includes needle hub means for attaching to a proximal end of the needle. The apparatus further includes needle cam means for accepting the needle hub means for coupling thereto. The needle cam means is disposed in a frame of the medical instrument at a distal end thereof.
The above-mentioned object may also be achieved by a method for coupling a needle to a medical instrument. The method includes a step of attaching a needle hub to the needle, the needle hub including first registration ribs on an external surface thereof. The method also includes a step of registering the first registration ribs of the needle hub with second registration ribs on an inner surface of a needle cam disposed on a distal frame portion of the medical instrument. The needle hub is coupled to the needle cam as a result, thereby coupling the needle to the medical instrument in a non-integral manner.